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Biomedical subjects

J Quintana

Publications and source records attributed to J Quintana.

At least 73 records · Page 4Linked to original sources
PubMed1988

Platelet MAO deamination of serotonin in depressed patients. Changes after imipramine treatment and clinical correlations.

Monoamine oxidase (MAO) in blood platelets has been used as a model to study MAO in the central nervous system, where disorders in serotonergic systems are thought to occur in depression. Inconsistent changes in platelet MAO of depressed patients have been reported when several substrates other than serotonin (5-HT) have been used. To correlate changes in platelet MAO activity with the enzyme activity in central serotonergic systems, the platelet MAO activity of depressed patients (first unmedicated and then after 3 weeks and 2 months of imipramine treatment) and normal controls was measured using 5-HT as substrate. The results showed that there is a steady, measurable platelet MAO activity with that substrate. This activity was significantly higher in unmedicated depressed patients than in controls, and it decreased progressively with imipramine treatment, reaching a normal level when the patients were clinically recovered from depression after 2 months of therapy.

Adult↗
PubMed1986

A microelectrode for depth recording in awake animals.

The manufacture is described of a metal, glass-coated microelectrode for single-cell recording from deep structures of the brain during behavioral testing. It is thin, long, and straight, and has excellent electrical properties.

Animals↗
PubMed1985

Adenosine and related nucleotides alter calcium uptake in depolarized synaptosomes of torpedo electric organ.

Calcium has been shown to enter cholinergic synaptosomes transiently during potassium-induced depolarization, in which ACh and ATP are released together. Because junctional ATP is rapidly hydrolyzed by extracellular ATPases, I studied and compared the roles of ATP, ADP, AMP, and adenosine (Ade) on the control of calcium uptake during depolarization. Pure cholinergic synaptosomes of Torpedo fish electric organ were depolarized by high potassium concentrations and the amount of calcium uptake was then measured in the presence of equal concentrations of Ade and its related nucleotides. Calcium uptake was more inhibited when the nucleotide was less phosphorylated. Thus, Ade was the greatest inhibitor. Because Ade is quickly and actively taken up from the extracellular medium by synaptosomes and converted intracellularly to ATP, I also measured the capacity of Ade, after its initial inhibitory action, to reactivate the calcium uptake. After a short preincubation with Ade, the later uptake of calcium was enhanced. The combined results support a complete role of adenosine and related nucleotides in the control of calcium movement across the presynaptic membrane.

Adenine Nucleotides↗
PubMed1985

Keratosis punctata of the palmar creases.

A 44-year-old man with no family history of keratosis punctata showed, at the age of 19 years, punctiform hyperkeratotic elements confined exclusively to the flexion creases of the palms and digits. We review the literature and comment on the clinical, histologic, and therapeutic aspects of this exceptional dermatosis.

Adult↗
PubMed1982

Infantile embryonal carcinoma of testis.

Between 1968 and 1979 we treated 19 patients with infantile embryonal carcinoma of the testis. All 10 patients treated with orchiectomy plus chemotherapy (methotrexate, actinomycin D and cyclophosphamide) are well with no evidence of disease, whereas 2 of 4 who underwent orchiectomy alone and 2 of 5 treated with orchiectomy plus lymphadenectomy are dead. Infantile tumors with yolk sac elements have an apparent increase in hematogenous spread and, despite negative lymph nodes in the majority, a significant number have subsequent disseminated metastases. This suggests that infantile embryonal carcinoma is different from the adult type and implies that in clinical stage A disease retroperitoneal lymphadenectomy is unnecessary. The alpha-fetoprotein correlates with the presence of yolk sac tissue in biopsy and the radioimmunoassay level assists in monitoring the treatment.

Child, Preschool↗
PubMed1978

[Study of the thyroid function by the I-M TRH test (2 mg) (author's transl)].

The responses of TSH, T3 and T4 to intramuscular administration of 2 mg of TRH were compared in the same subjects to those observed after intravenous injection of 200 microgram of TRH. In 12 normal subjects the TSH and T3 peaks were significantly higher after intramuscular injection. There was no difference in T4 levels. In 15 patients: 5 toxic adenomas after surgery and 10 Graves' disease after treatment the results were comparable for TSH and T3 by the two routes.

Adult↗
PubMedDate not supplied

Platelet serotonin uptake dynamic changes in depression: effects of long-term imipramine treatment and clinical recovery.

The characteristics of the serotonin uptake mechanism were measured in blood platelets of depressed patients before treatment and after 3 weeks and 2 months of imipramine therapy. The results were then compared with data from normal volunteers. In the unmedicated, depressed patients, platelets showed two affinity components of serotonin uptake. Both affinity states differed, in opposite directions, from the platelet serotonin uptake in normal volunteers. In the latter, a two-state model was more difficult to establish. Successful imipramine treatment progressively normalized the platelet serotonin uptake changes seen in unmedicated patients. Those changes allowed the membrane to deal with a wider than normal range of extracellular serotonin concentration; they might reflect neuronal compensatory changes resulting from altered extraneuronal serotonin concentrations and leading, directly or via presynaptic receptors, to balancing them. Imipramine treatment assists the adaptive process and accelerates the clinical recovery.

Adult↗
PubMedDate not supplied

Spatial and temporal factors in the role of prefrontal and parietal cortex in visuomotor integration.

The effects of reversible lesion--by cooling--of dorsolateral prefrontal and posterior parietal cortex were studied in rhesus monkeys performing a cognitive visuomotor integration task. Correct performance required the use of a learned set of cue-response contingencies, some spatial and some nonspatial; in some cases, the task required the short-term retention, through a delay, of the color of the cue or its implicit response direction. Prefrontal cooling impaired performance of the task regardless of its spatial demands, an effect that increased with delay. Parietal cooling, on the other hand, only impaired performance if the task demanded the processing and retention of spatial information (i.e., if spatial active memory was required). Parietal effects were not related to delay. Both prefrontal and, even more, parietal cooling increased response time in all task contingencies. Thus, the results dissociate the respective contributions of the prefrontal and the posterior parietal cortex to the temporal and spatial aspects of information processing in visuomotor performance. They indicate that posterior parietal areas participate in spatial processing and in active memory of spatial information, whereas prefrontal areas subserve a broader role of visuomotor processing and cross-temporal integration of both spatial and nonspatial information.

Analysis of Variance↗
PubMedDate not supplied

From perception to action: temporal integrative functions of prefrontal and parietal neurons.

The dorsolateral prefrontal cortex (DPFC) and the posterior parietal cortex (PPC) are anatomically and functionally interconnected, and have been implicated in working memory and the preparation for behavioral action. To substantiate those functions at the neuronal level, we designed a visuomotor task that dissociated the perceptual and executive aspects of the perception-action cycle in both space and time. In that task, the trial-initiating cue (a color) indicated with different degrees of certainty the direction of the correct manual response 12 s later. We recorded extracellular activity from 258 prefrontal and 223 parietal units in two monkeys performing the task. In the DPFC, some units (memory cells) were attuned to the color of the cue, independent of the response-direction it connoted. Their discharge tended to diminish in the course of the delay between cue and response. In contrast, few color-related units were found in PPC, and these did not show decreasing patterns of delay activity. Other units in both cortices (set cells) were attuned to response-direction and tended to accelerate their firing in anticipation of the response and in proportion to the predictability of its direction. A third group of units was related to the determinacy of the act; their firing was attuned to the certainty with which the animal could predict the correct response, whatever its direction. Cells of the three types were found closely intermingled histologically. These findings further support and define the role of DPFC in executive functions and in the temporal closure of the perception-action cycle. The findings also agree with the involvement of PPC in spatial aspects of visuomotor behavior, and add a temporal integrative dimension to that involvement. Together, the results provide physiological evidence for the role of a prefrontal-parietal network in the integration of perception with action across time.

Animals↗
PubMedDate not supplied

[Retinoblastoma].

Explore the source record for details and available documents.

Child, Preschool↗
PubMedDate not supplied

[Frontal lobe dysfunction in patients with epilepsy and chronic psychosis].

PATIENTS AND METHODS: Fifty patients diagnosed as having epileptic crises were given neuropsychological tests including the Wechsler Adult Intelligence Scale or WAIS, Luria's neuropsychological test and a quantitative EEG examination. Multivariate analysis was done of the following variables: presence or absence of inter-octal psychosis, onset of crises before the age of 10 years, frequency of crises or status epilepticus greater than 100, known cause or otherwise of epilepsy, and the presence of more than one type of crisis in a particular patient. The working hypothesis was to show that the association of epilepsy and psychosis causes alterations in superior psychic functions (SPF) particularly of the frontal lobes. The WAIS test, intelligence, verbal and executive quotients and the 11 subtests were evaluated using multivariate analysis (ANOVA) conditioned by the different variables studied. The broad band spectral measurements of the quantitative EEG (BBSM) were studied using a statistical programme (COMPARA) by which the groups of individuals were compared with a standard group, using the Student t and Fisher tests. The different BBSM variables studied were: absolute power, relative power and total dominant frequency. RESULTS: Amongst the most important results were: reduction in the performance scale of epileptics with chronic psychosis, alterations on the verbal scale in epileptics with more than one type of crisis, presence of frontal and fronto-temporal dysfunction in epileptics with chronic psychosis and negative signs of schizophrenia. On the quantitative EEG in epileptics with psychosis there was abnormally slow activity predominantly in the frontal lobes. CONCLUSIONS: From the overall results we may conclude that in patients with epilepsy and chronic psychosis there is cortical dysfunction of the frontal lobe.

Adult↗